The present invention relates to surgical apparatus including a pair of instruments, sheathing means for the instruments and actuating means for extending one or the other instrument from the sheathing means, and more particularly to such apparatus which is a surgical combination inject and snare apparatus.
Commonly owned copending U.S. patent application Ser. No. 08/248,504, filed May 24, 1994, now U.S. Pat. No. 5,542,948, discloses surgical apparatus comprising a first instrument (which may be an injection needle), a second instrument (which may be a snare) and sheathing means (such as a catheter) for sheathing both instruments. Actuator means are provided for simultaneously extending the first instrument relative to the distal end of the sheathing means in a first direction and retracting the second instrument in an opposed second direction relative to the distal end of the sheathing means, and for simultaneously extending the second instrument relative to the distal end of the sheathing means in the first direction and retracting the first instrument in the second direction relative to the distal end of the sheathing means. In other words, the actuator means extends one of the two instruments while simultaneously retracting the other instrument.
The patented apparatus is used by inserting the distal tip thereof into a patient with both the first and second instruments being in an intermediate position, wherein both are covered by the sheathing means. When the distal tip of the sheathing means is properly positioned, the first instrument (typically an injection needle) is extended beyond the sheathing means and into an adjacent polyp. Fluid is then introduced into the polyp causing it to project further inwardly from the wall. At this point the first instrument is withdrawn, and the second instrument (typically a snare) is extended and used to snare the inwardly protruding polyp. This snare may be used simply for physical cutting of the polyp, or it may be electrified to facilitate separation of the polyp from the wall with minimal bleeding. The detached polyp may be withdrawn through the distal tip of the surgical apparatus, or it may be trapped within the interior of the sheathing means to facilitate its withdrawal with the distal tip of the surgical apparatus.
The aforementioned surgical apparatus is susceptible to improvement. For example, in the aforementioned surgical apparatus the force which must be exerted by the surgeon to extend the snare must also include the force required to overcome the friction involved in dragging the injection needle proximately through the sheathing means. A surgeon would be able to manipulate the snare with greater accuracy if he had to exert only the force required to move the snare, and not simultaneously also the force required to move the injection needle.
Further, the surgeon has to manually maintain the injection needle in the extended position during the entire time that it takes to inject sufficient fluid therethrough to cause the polyp to project inwardly from the wall, this step being unnecessarily time-consuming to a surgeon who might have better use for at least one of his hands during this interval if he could lock the needle into an injection position.
Ideally, it should not be necessary for the surgeon to manually retract the injection needle when it is no longer needed, and he should be able to rely on some type of automatic needle retraction mechanism which he could actuate.
The injection needle, like the snare, can be extended a variable and sizable distance distally relative to the distal tip of the sheathing means. However, while it is desirable for the snare to be extendable a variable and sizable distance up to about 5 inches, it is better for the injection needle to be extendable only about 0.75 inch, just sufficient to reach the interior of the polyp. A shorter throw of the needle would also enable a greater curve at the distal end of the sheathing means without danger of the needle becoming caught in the sheathing means (i.e., the catheter) during extending of the needle.
Further, the possibility exists that the injection needle will accidentally be extended when the surgeon's intent is to extend the snare. Thus it would be desirable to have a safety mechanism which had to be disabled in order to enable extension of the needle.
Surgeons acquire great expertise in utilizing hypodermic-type handles (that is, surgical apparatus operated by the first three fingers of a hand), but are typically less familiar with the wheel arrangement of the patented apparatus which must be rotated, say, to withdraw the injection needle and extend the snare.
Accordingly, it is an object of the present invention to provide surgical apparatus, such as a combination inject and snare apparatus, wherein the movement of the first instrument (typically an injection needle) is independent of the movement of the second instrument (typically a snare), thereby to reduce the force which must be exerted during either movement.
Another object is to provide such apparatus which in one embodiment maintains the injection needle in the extended position without further action on the part of the surgeon.
A further object is to provide such surgical apparatus which in one embodiment provides a mechanism for automatic retraction of the needle when it is no longer required.
It is another object to provide such surgical apparatus which in one embodiment incorporates a locking mechanism which must be unlocked in order to enable extension or retraction of the needle.
It is also an object of the present invention to provide such surgical apparatus which in one embodiment enables the snare to be extended a variable and sizeable distance while the injection needle is extendable only a much shorter distance, but typically the full extent of the shorter distance.